Banded cigarette paper with reduced ignition propensity

ABSTRACT

A cigarette made from cigarette paper comprising a base web and at least one banded region comprising iron oxide nanoparticles. The at least one banded region has a porosity less than a porosity of the base web such that the at least one banded region exhibits a slower burn rate compared to adjacent non-banded regions.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority under 35 U.S.C. §119(e) to U.S. provisional Application No. 60/877,640, filed Dec. 29, 2006, the entire content of which is incorporated herein by reference.

SUMMARY

Provided is cigarette paper comprising a base web and at least one banded region comprising a burn promoter in the form of iron oxide nanoparticles. The at least one banded region has a porosity less than a porosity of the base web such that the at least one banded region exhibits a slower burn rate compared to the burn rate of adjacent non-banded regions.

The at least one banded region may comprise a material selected from the group consisting of cellulose, starch, alginate, and polyvinyl acetate. Non-banded regions adjacent the at least one banded region may comprise iron oxide nanoparticles or iron oxide nanoparticles may only present in the at least one banded region.

Also provided is a cigarette comprising the cigarette paper. The cigarette preferably does not self-extinguish in free burn conditions, but does self-extinguish in the at least one banded region upon contacting a combustible substrate. Additionally provided is a method of making a cigarette comprising wrapping the cigarette paper around tobacco cut filler to make a tobacco rod, slicing the tobacco rod into tobacco rod segments and optionally attaching filters to the tobacco rod segments.

Further provided is a method of making cigarette paper comprising forming at least one banded region comprising a burn promoter in the form of iron oxide nanoparticles on a base web. The at least one banded region has a porosity less than a porosity of the base web such that the at least one banded region exhibits a slower burn rate compared to adjacent non-banded regions.

In an embodiment, the at least one banded region comprises cellulose. The at least one banded region may be formed by discharging a slurry comprising iron oxide nanoparticles and cellulose on the base web or the base web may comprise iron oxide nanoparticles and the at least one banded region may be formed by discharging a slurry comprising cellulose on the base web.

In an embodiment, the at least one banded region comprises starch. The at least one banded region may be formed by printing a composition comprising iron oxide nanoparticles and starch on the base web or the base web may comprise iron oxide nanoparticles and the at least one banded region may be formed by printing a composition comprising starch on the base web.

In addition, provided is a method of making a cigarette comprising making cigarette paper, wrapping the cigarette paper around tobacco cut filler to make a tobacco rod, slicing the tobacco rod into tobacco rod segments and optionally attaching filters to the tobacco rod segments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of a partially unwrapped cigarette including a base web and banded cigarette paper where the paper width is exaggerated.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

It has been surprisingly discovered that cigarettes made from cigarette paper having banded regions comprising iron oxide nanoparticles as a burn promoter have statistically fewer occurrences of self-extinguishment in free burn conditions, but will pass American Society of Testing and Materials (ASTM) Standard E2187-02b (i.e., self-extinguish upon contacting a combustible substrate), which is incorporated herein in its entirety by this reference thereto.

Banded Cigarette Paper

The presently disclosed banded cigarette paper may be manufactured by a method and using an apparatus, such as that disclosed in commonly owned U.S. Pat. No. 6,596,125, hereby incorporated by referenced in its entirety, which relates to method and apparatus for applying a predetermined pattern of add-on material to a base web, preferably in the form of bands, and more particularly, to a method and apparatus for producing cigarette papers having banded regions of additional material. As disclosed therein, the banded regions may exhibit a slower burn rate in comparison to those regions of the base sheet between the banded regions. Further disclosures related to banded cigarette paper include commonly owned U.S. Pat. Nos. 5,417,228, 5,474,095, and 5,534,114, each hereby incorporated by reference in its entirety.

Referring now to FIG. 1, the banded cigarette paper 12 is wrapped about a column of tobacco to form the tobacco rod 20 of a cigarette 10, which will at the banded regions 14 exhibit a slower burn rate in comparison to those regions of the base web 16 between the banded regions 14.

Accordingly, the banded regions 14 may be formed by discharging or spraying a slurry containing an add-on material on the base web 16. The base web 16 of the presently disclosed banded cigarette paper 12 is preferably comprised of cellulosic pulp, such as, for example, flax pulp or wood pulp. The add-on material in the slurry may comprise, for example, additional pulp, starch, alginate, cellulose, or polyvinyl acetate. The add-on material preferably comprises cellulose.

Alternatively, the banded regions 14 may be formed by printing, preferably gravure printing, an aqueous film-forming composition on the base web. The film-forming composition may include an add-on material in the form of a film-forming compound, such as, for example, starch, preferably an oxidized starch, alginate, carrageenan, guar gum, or pectin. The film-forming compound preferably comprises starch. Optionally, the film-forming compound may comprise one or more filler materials such as, for example, calcium carbonate or citrate.

The permeability of the banded regions 14 of the presently disclosed banded cigarette paper 12 is lower than the permeability of adjacent non-banded regions. Thus, the static burn rate of a cigarette comprising the presently disclosed banded cigarette paper 12 is substantially decreased in the banded regions 14, which have decreased porosity. The rate of oxygen diffusion through the paper in these regions is thereby decreased, retarding combustion of the cigarette.

Burn Promoter

Incorporation of burn promoter into banded regions of the cigarette paper lessens the statistical occurrences of self-extinguishment in free burn conditions. The effectiveness of the burn promoter is sensitive to oxygen level. Accordingly, as oxygen is abundant in free burn conditions, the effectiveness of the burn promoter is sufficient to overcome the self-extinguishing characteristic of the banded regions of the cigarette paper. Conversely, as oxygen is not abundant in the conditions of ASTM E2187-02b, the effectiveness of the burn promoter is not sufficient to overcome the self-extinguishing characteristic of the banded regions of the cigarette paper.

Thus, the burn promoter may be incorporated into the add-on material of the banded regions of the cigarette paper or added to the banded regions of the cigarette paper separately from the add-on material of the banded regions, either before or after addition of the add-on material. Alternatively, it is contemplated that the base web of the presently disclosed banded cigarette paper may comprise the burn promoter and the add-on material of the banded regions not comprise additional burn promoter.

The term “burn promoter” as used herein refers to any substance known to increase the rate at which the smolder process of such materials as paper, cloth and plastic takes place. Such a substance may contribute to the free burn of a cigarette. Preferably, a reduced ignition propensity cigarette self-extinguishes when placed onto a surface, but continues to smolder when the cigarette is freely suspended, such as within the holder of an ashtray or held between puffs. This latter attribute is known as “free burn.” To that end, a burn promoter works to maintain the balance between self-extinguishment and free burn.

The burn promoter comprises iron oxide nanoparticles, such as, for example, NANOCAT® Superfine Iron Oxide (SFIO) by MACH I, Inc. (King of Prussia, Pa.). By “nanoparticles” is meant that the particles have an average particle size of less than a micron. The preferred average particle size is less than about 100 nm, with a preferred surface area of from about 20 m²/g to about 400 m²/g, more preferably from about 200 m²/g to about 300 m²/g.

Tobacco

Examples of suitable types of tobacco materials that may be used include, but are not limited to, flue-cured tobacco, Burley tobacco, Maryland tobacco, Oriental tobacco, rare tobacco, specialty tobacco, genetically modified tobacco, blends thereof and the like. The tobacco material may be provided in any suitable form, including, but not limited to, tobacco lamina, processed tobacco materials, such as volume expanded or puffed tobacco, processed tobacco stems, such as cut-rolled or cut-puffed stems, reconstituted tobacco materials, blends thereof, and the like. Tobacco substitutes may also be used.

In traditional cigarette manufacture, the tobacco is normally used in the form of cut filler, i.e., in the form of shreds or strands cut into widths ranging from about 1/10 inch to about 1/20 inch or even about 1/40 inch. The lengths of the strands range from between about 0.25 inch to about 3.0 inches. The cigarettes may further comprise one or more flavors, or other suitable additives (e.g., burn additives, combustion modifying agents, coloring agents, binders, etc.).

Cigarette Production

During cigarette production or fabrication, tobacco is placed along strips of cigarette paper reaching up to 6,000 meters in length. The paper is closed over the tobacco, making one long article known as a “rod,” ready to be sliced into individual cigarette portions and these portions can be attached to filter rod segments, which are cut into filtered cigarettes. For instance, a continuous rod can be cut into segments, which are attached to double length filter segments. A slicer then slits the lengths in two, dividing the double length filter equally in half to form two cigarettes.

EXAMPLES

In a free burn test, a cigarette having two banded regions comprising cellulose, formed according to the process of spraying add-on slurry discussed above and which exhibited a slower burn rate compared to adjacent non-banded regions, self-extinguished at the first banded region in horizontal free burn conditions. In contrast, three cigarettes having two banded regions comprising cellulose, also formed according to the process of spraying add-on slurry discussed above and which exhibited a slower burn rate compared to adjacent non-banded regions, but which further comprised NANOCAT® SFIO, did not self-extinguish at the first banded region in horizontal free burn conditions. The NANOCAT® SFIO was added to the banded regions by applying a slurry comprising 2.5 g of NANOCAT® SFIO, 20 mL water, and 20 mL methanol on the banded regions using a cotton swab. After the first banded region was burned through in horizontal free burn conditions, each cigarette was placed on 10 sheets of Whatman No. 1 (150 mm) filter paper. Each cigarette self-extinguished at the second banded region.

Five cigarettes having iron oxide painted on slurry banded regions tested according to ASTM E2187-02b yielded 1 total burn and 4 self-extinguishments. Of the three cigarettes having two iron oxide painted on slurry banded regions tested for self-extinguishment in free burn conditions at 90 degrees from horizontal, two cigarettes extinguished at the first banded region and one cigarette burned through the first banded region and extinguished at the second banded region. The two cigarettes that extinguished at the first banded region were relit and tested for self-extinguishment in free burn conditions at 45 degrees from horizontal, resulting in total burns. Two additional cigarettes having iron oxide painted on slurry banded regions tested for self-extinguishment in free burn conditions at 45 degrees from horizontal also resulted in total burns.

In Tables 1-3 an ASTM E2187-02b designation of “pass” corresponds to a cigarette self-extinguishing before the filter line, while an ASTM E2187-02b designation of “fail” corresponds to cigarette burning all the way to the filter line. In Tables 1-3 “self-extinguishment” refers to testing for self-extinguishment in free burn conditions, with a self-extinguishment designation of “pass” corresponds to a cigarette burning all the way to the filter line and a self-extinguishment designation of “fail” corresponds to a cigarette self-extinguishing before the filter line.

Hand-made cigarettes having banded regions comprising various NANOCAT® SFIO weight percentages were tested according to ASTM E2187-02b and “self-extinguishment” in a horizontal position, at 45 degrees from horizontal, and at 90 degrees from horizontal (vertical). Each test was run on five cigarettes for each NANOCAT® SFIO weight percentage. Thus, in Table 1, a passage percentage of 100% refers to 5 out of 5, a passage percentage of 80% refers to 4 out of 5, and a passage percentage of 0% refers to 0 out of 5. The NANOCAT® SFIO was applied to the cigarettes according to the spraying process discussed above, with the slurry comprising 1.5 weight % flax plus NANOCAT® SFIO, and the balance being water with or without small amounts of additives.

TABLE 1 Self- Extinguishment (Passage %) Iron Oxide Iron Oxide/ ASTM E2187-02b 45 degrees from 90 degrees from (Weight %) Flax (Passage %) Horizontal Horizontal Horizontal 0.23 0.156 100 100 100 100 0.45 0.300 100 80 100 80 0.67 0.448 0 100 100 100

Table 1 shows that increasing the ratio of iron oxide to flax in the banded regions beyond an optimal level may lead to increased self-extinguishment failure, and eventually to ASTM E2187-02b failure.

Tables 2 and 3 relate to embodiments wherein the banded regions are formed from film-forming compositions comprising starch, as discussed above with different amounts of iron oxide. Specifically, Table 2 provides results for testing of cigarettes having banded regions comprising 18% FLOKOTE 64 (18 grams of FLOKOTE 64/100 grams of water), an oxidized corn starch from National Starch & Chemical Company (Bridgewater, N.J.), plus NANOCAT® SFIO. While the banded regions were applied by hand-brushing, in commercial production such banded regions would preferably be applied by printing.

TABLE 2 18% FLOKOTE 64 with NANOCAT ® SFIO Self- Horizontal Extinguishment Iron Iron ASTM Self- at 90 degrees Oxide Oxide/ E2187-02b Extinguishment from Horizontal (Grams) Starch Pass Fail Pass Fail Pass Fail 0.9 0.05 3 0 0 3 0 3 1.8 0.10 3 0 0 3 0 3 2.7 0.15 3 0 0 3 0 3 3.6 0.20 3 0 1 2 0 3 5.4 0.30 3 0 1 2 0 3 7.2 0.40 2 1 3 0 1 2 8.1 0.45 3 0 3 0 0 3 9.0 0.50 2 1 3 0 2 1 9.9 0.55 2 1 3 0 3 0

According to Table 2, ratios of NANOCAT® SFIO to dry starch of 0.05, 0.10, and 0.15 yielded passage rates of 100% (3 out of 3) for ASTM E2187-02b, but only 0% (0 out of 3) for self-extinguishment both at horizontal and at 90 degrees from horizontal. Ratios of NANOCAT® SFIO to dry starch of 0.20 and 0.30 yielded passage rates of 100% (3 out of 3) for ASTM E2187-02b, but only 33% (1 out of 3) for self-extinguishment at horizontal and 0% (0 out of 3) for self-extinguishment at 90 degrees from horizontal. Thus, with 18% FLOKOTE 64, a ratio of NANOCAT® SFIO to dry starch of 0.40-0.55 is preferable.

Table 3 provides results for testing of cigarettes having banded regions comprising 30% FLO-MAX 8 (30 grams of FLO-MAX 8/100 grams of water), an oxidized tapioca starch from National Starch & Chemical Company (Bridgewater, N.J.), plus NANOCAT® SFIO. Although in this test the banded regions were applied by hand-brushing, in commercial production such banded regions would preferably be applied by printing.

TABLE 3 30% FLO-MAX 8 with NANOCAT ® SFIO Self- Horizontal Extinguishment Iron Iron ASTM Self- at 90 degrees Oxide Oxide/ E2187-02b Extinguishment from Horizontal (Grams) Starch Pass Fail Pass Fail Pass Fail 6.0 0.20 3 0 0 3 0 3 9.0 0.30 3 0 0 3 0 3 10.5 0.35 3 0 2 1 0 3 12.0 0.40 3 0 3 0 3 0 13.5 0.45 0 3 3 0 3 0

According to Table 3, ratios of NANOCAT® SFIO to dry starch of 0.20 and 0.30 yielded passage rates of 100% (3 out of 3) for ASTM E2187-02b, but only 0% (0 out of 3) for self-extinguishment both at horizontal and at 90 degrees from horizontal. Thus, with 30% FLO-MAX 8, a ratio of NANOCAT® SFIO content to dry starch of 0.35-0.45 is preferable.

While various embodiments have been described, it is to be understood that variations and modifications may be resorted to as will be apparent to those skilled in the art. Such variations and modifications are to be considered within the purview and scope of the claims appended hereto. 

1. Cigarette paper comprising: a base web; and at least one banded region comprising an add-on material and a burn promoter, wherein the burn promoter comprises iron oxide nanoparticles in sufficient quantity to reduce statistical occurrence of self-extinguishment; and wherein the at least one banded region has a porosity less than a porosity of the base web such that the at least one banded region exhibits a slower burn rate compared to adjacent non-banded regions.
 2. The cigarette paper of claim 1, wherein non-banded regions adjacent the at least one banded region comprise iron oxide nanoparticles.
 3. The cigarette paper of claim 1, wherein iron oxide nanoparticles are only present in the at least one banded region.
 4. The cigarette paper of claim 1, wherein the add-on material comprises cellulose.
 5. The cigarette paper of claim 1, wherein the add-on material comprises starch.
 6. The cigarette paper of claim 5, wherein a ratio of iron oxide nanoparticles to starch is in the range of 0.35-0.55.
 7. A cigarette comprising: tobacco material; and a cigarette paper wrapped around said tobacco material, said cigarette paper comprising: a base web; and at least one banded region comprising an add-on material and a burn promoter, wherein the burn promoter comprises iron oxide nanoparticles in sufficient quantity to reduce statistical occurrence of self-extinguishment; and wherein the at least one banded region has a porosity less than a porosity of the base web such that the at least one banded region exhibits a slower burn rate compared to adjacent non-banded regions.
 8. The cigarette of claim 7, wherein the cigarette does not self-extinguish in free burn conditions.
 9. The cigarette of claim 7, wherein the cigarette self-extinguishes in the at least one banded region when in contact with a combustible substrate.
 10. A method of making a cigarette comprising: wrapping the cigarette paper of claim 1 around tobacco cut filler to make a tobacco rod; slicing the tobacco rod into segments; and optionally attaching a filter to one of the segments.
 11. A method of making cigarette paper comprising forming at least one banded region comprising iron oxide nanoparticles on a base web, wherein the at least one banded region has a porosity less than a porosity of the base web such that the at least one banded region exhibits a slower burn rate compared to adjacent non-banded regions.
 12. The method of claim 11, wherein the at least one banded region comprises cellulose.
 13. The method of claim 12, wherein the at least one banded region is formed by discharging a slurry comprising iron oxide nanoparticles and cellulose on the base web.
 14. The method of claim 12, wherein the base web comprises iron oxide nanoparticles.
 15. The method of claim 14, wherein the at least one banded region is formed by discharging a slurry comprising cellulose on the base web.
 16. The method of claim 11, wherein the at least one banded region comprises starch.
 17. The method of claim 16, wherein a ratio of iron oxide nanoparticles to starch is in the range of 0.35-0.55.
 18. The method of claim 16, wherein the at least one banded region is formed by printing a composition comprising iron oxide nanoparticles and starch on the base web or by printing a composition comprising starch on the base web.
 19. The method of claim 16, wherein the base web comprises iron oxide nanoparticles.
 20. A method of making a cigarette comprising: making cigarette paper according to claim 11; wrapping the cigarette paper around tobacco cut filler to make a tobacco rod; slicing the tobacco rod into segments; and optionally attaching a filter to one of the segments. 